The present disclosure relates generally to a gas turbine. More particularly, the present disclosure relates to a turbine including a flue gas recirculation combustor, wherein NOx (nitrogen oxides) is reduced by recirculating the flue gas to lower the oxygen concentration of premixed fuel (mixture of mist fuel and air) in a combustor chamber that combusts the premixed fuel of fuel and air (mixture of mist fuel and air) injected from a nozzle, NOx (nitrogen oxides) can be reduced by recirculating the flue gas to lower the oxygen concentration in the premixed fuel.
A gas turbine is a rotary type heat engine that drives a turbine with high temperature and high pressure combustion gas. To create the high-temperature and high-pressure combustion gas, a mixture of fuel and air injected from the combustion nozzle must be combusted in the combustion chamber provided in the combustor. While combustion continues, the gas turbine continues to operate until fuel and air supply (especially, the fuel supply) is stopped.
In the gas turbine, self-sustaining combustion of fuel/air mixture supplied to the combustion chamber by the heat generated occurs only when the initial combustion of the fuel/air mixture is initiated and a high temperature environment is created in the combustion chamber. Accordingly, in order to operate a stopped gas turbine, an igniter is used to generate an artificial combustion for the initial mixture.
The igniter may be of the type that emits electrical energy or uses electrical energy to heat an end portion thereof, or it may be of an ignition torch type that burns the fuel.
The fuel/air mixture combusted in the combustor chamber emits a large amount of nitrogen oxides (NOx). In this case, nitrogen oxides, as pollutants, must be reduced to avoid environmental pollution. To achieve this, a method of suppressing the generation of nitrogen oxides by reducing the oxygen concentration contained in the combusting fuel/air mixture can be used.
In the combustion process of a conventional gas turbine, the temperature of the combustion process is controlled to limit the emission of nitrogen oxides. However, it is very difficult to control the oxygen concentration only with an internal device of the gas turbine. As a result, the efficiency of reducing the nitrogen oxide concentration is low. Accordingly, securing the effect of sufficiently reducing the nitrogen oxide concentration only by the conventional structure has been problematic, so structural improvement is needed.